Some of Bradley's class-mates at Blackhall Primary School performed on the track.

Olivia and Georgia, from Bishop Cuthbert, were filmed while they sang with the youngsters, with the footage to be used in a music video accompanying the song.

The sisters launched a Christmas song for him last year, with 'Bradley - Our Superhero (A Christmas Wish)' reaching number 12 in the charts.

The latest song was chosen because of Bradley's smile, which has touched the hearts of so many people around the world.

Speaking after the song was announced earlier this month, Olivia said: "We wanted to do this song because of Bradley's smile.

"In every single photo on Facebook he is smiling.

"We can't imagine what he is going through or what his family is going through, but his smile has captured the hearts of not only us, but the nation and the world, so we wanted to do this for such an amazing little boy."

Georgia added: "We hope that everyone will get behind it to help make more memories for Bradley, support Bradley and his family and raise money, not only for Bradley but for other children."